Back into PHP.

Hey guys, I've decided to get back into coding in PHP as it's been a good few years since I did any work in it. I had the idea of setting up a web page, and having it update the title. Like

Website - (Page name (Home/About/Contact))

So if I went to the "About Us" page, it would change the title to Website - About Us. But I'm having a bit of trouble with the variable, as it doesn't update no matter what I do/change. My simple file is below if anyone is able to help.